Vacuum circuit breaker



Aug. 18, 1931.

c. KABELE 1,819,420

VACUUM CIRCUIT BREAKER Filed Aug. 22, 1927 2 Sheets-Sheet l Inventor Attornqy Aug. 18, 1931. c. KABELE VACUUM CIRCUIT BREAKER 2 Sheets-Sheet 2 Filed Aug. 22, 1 927 [n ventor Clarence/fa ZeZd,

V Attorney Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE CLARENCE KAIBELE, OF SCHENECTADY, NEW YORK vacuum CIRCUIT BREAKER Application filed August 22, 1927. Serial No. 214,734.

The essential object of the invention is to provide means enabling a high voltage on cuit to be automatically broken within a vac= uum container when subjected to an overload, without the creation of a disruptive arcing, such as commonly occurs when separating the contact members, and to this end I have designed the breaking action to be controlled by a plurality of magnetic forces, including a magnetic force arranged externally of the container and comprising separate forces to actuate the contacts for opening and closing, and an internal magnetic force created by the circuits through the arrangement of the contact members with eachoother and operating to resist the action of the external magnetic force, when arranged for opening the circuit, until the current in the circuit has been reduced to zero or an approximate zero point permitting the safe breaking thereof, at which point the arcing is reduced to a minimum or entirely eliminated.

A further object is to provide a circuit breaker of this character which may be controlled from a remote point, which is simple and practical in construction, eflicient and reliable in performance, free from any mechanically operated parts which are apt to become out of order and otherwise well adapted for the purposes for which the same is intended.

.Other objects and advantages reside in the special construction and combination of the various elements, reference being had to the accompanying drawings forming a part hereof, whereof v Figure 1 is a vertical sectional view through the vacuum container showing the V circuit breaking elements arranged in position therein.

Figure 2 is a transverse sectional view taken along a line 2-2 of Figure 1, and

Figure 3 is a diagrammatic view of a conventional feeder circuit showing the electrical connection of a single phase breaker element.

. Heretofore the use of an automatic vacuum circuit breaker for high voltage circuits has been found impracticable due principally to the failure to produce a satisfactory vacuum container embodying the desirable features of the glass container and overcoming the fragile nature thereof, glass containers being superior in all respects except for the inability thereof to withstand the heating and burning created by severe arcing'during the breaking of the circuit and by the mechani-f cal stresses and shocks caused by opening and closing contacts of a conventional type. Ex-

perience has shown'the creation of a safe and practlcal vacuum" circuit breaker involves the solution of a three fold problem: First,

the led-in must be of a certain area in cross section; flexible toa highdegree andvacuum tight. Second, the internal circuit breaker mechanism must operate in a positive and simple manner, must follow a straight line conducting path through the container so as to avoid magnetic bending stresses on overloads, must not cause shocks or jars when operating, must be in good contact with the glass walls of the container to prevent heat choking, and must not require any attention or adjustment after the breaker is'once as sembled. Third, because of the fragile nature of the device, the contacts must part on or at a very near zero current in order to prevent arcing, which in a heavy current would be destructive.

In the construction of my invention, I have created a vacuum circuit breaker which meets all theforegoing requirements and enables the use of the glass container as the most practical and efficient container for housing the circuit breaker.

Referring to the drawings in detail, I have shown the glass container constructed in sections, and comprising a cylindrical body section 5 having each end closed by concaved end sections 6, one of said end sections having a sealing tube 7 through which the vacuum may be created within the container. The lead-in wires indicated at 8 consist of a circular fringe of comparatively fine wire, any number of which may be provided and inserted separately through each end of the container and sealed between the cylindrical section 5 and the end 6 to form a vacuum tight fit therein. The external ends of each fringe of wire are fastened to a copper ring 9 serving as a connecting point for the circuit.

The wires are too thin individually to appreciably stress the glass and the whole leadin may be bent in any direction in a fairly flexible manner.

The circuit breaker mechanism consists of two separate units, one an internal contact making device, and the other an external magnetic actuating device. Within the cylinder section 5 of the container I arrange a pair of annular insulation rings 10 and 11 arranged in spaced relation with respect to each other about the inner wall of the container, the inner face of the lower ring 10 having a plurality of thin spring steel or other mag netic strips 12 secured thereto by their lower ends and arranged about the ring 10 in spaced relation with their upper or free ends inclined in a direction away from the wall of the cylinder 5. To the lower ends of the strip 12 are attached a suitable number ofthe leadin wires 8 thus forming contact members of such strip.

Upon the upper ring 11 I secure a plurality of plate members 13 arranged in spaced relation about the ring and in staggered relation with respect to the strip 12, the plates 13 constituting contact plates engageable by the strip 12, said strip being adapted to bridge the space between the adjacent contact plates so that each of the strips will be engageable with two of such plates. The contact plates 13 have a suitable number of the lead-in wires 8 attached thereto in a similar manner as the strips 12 whereby to form a continuous circuit through the container when the strips have been moved into contacting relation with the plates.

It is to be understood that these contact strips and plates 12 and 13 may be constructed of any suitable magnetic material adapted for magnetic attraction as hereinafter explained.

It will be noted that the electric path through the glass container is in a perfectly straight line when the contacts are closed as any bending in such path would cause severe stresses upon the glass when subjected to an overload. The internal sections of the leadin wire-s should be disposed against the inside of the cylindrical glass walls since in the event of being heated by overloads, the glass will absorb a large part of the heat and thus radiate it such as to minimize the danger of a heat choking.

About the outer wall of the cylindrical section 5 of the container and at a horizontal plane with each of the insulation rings 10 and 11 I provide a pair of iron rings 14 and 15 which may be laminated for alternating current excitation and arranged to adhere to the outer surface of the glass container in any suitable manner, a plurality of yokes 16 being arranged at spaced intervals about the circumference of the ring and connecting the same with each other. About each of the yokes 16, intermediate their ends, is arranged a pair of magnetizing coils, each lower coil being designated at A and each upper coil indicated at B, each of said coils, as indicated in. Figure 3 being adapted to receive current from a direct current source or from current or potential tansformers indicated at 17 having a rectifier 18 interposed therebetween, of the copper oxide-film type, which will permit such electro-magnet to constitute a direct current magnet. The resulting direct current goes directly through all of the coils B and through a relay 19 to the coils A.

When the breaker is arranged in closed position, the coils are magnetized with their fields extending in a similar direction to permit the continuous path of current therethrough. In this manner, the strips 12 are magnetized so asto draw the same in a direction toward the contact plates 13 tending to close the breaker element and creating a magnetic flux through the yoke and the contact strips and plates 12 and 13 respectively, whereby to retain the same in closed posi tion.

It is to be understood that the coils A may be connected either in series or in multiple and the coils B may be likewise connected in a similar manner.

The relay 19 is of a simple overload type having a trip coil 20 operated through a current transformer 21. The function of the relay is to reverse the current flow in coils A Whenever the same is tripped through an overload or manually. The overload trip coil 20 is operatively connected with a switch 22 whereby to reverse the direction of flow of current through the coils A.

The reversal of the direction of the current through such coils likewise reverses the poles' of the respective coils so as to cause the respective fields to oppose each other and thus seek separate paths. Thus the field of coil A repels the field of coil B although each field seeks to include all the magnetic material possible. Such action will cause the contact strips 12 and the contact plates 13 to repel each other and the force of such repulsion coupled with the opening spring action of the strips 12 will result in positively opening the breaker. It is to be understood however, that this opening action is not dependent upon the spring action of the strips 12 as the force of the magnetic repulsion is quite sufiicient to accomplish the opening action and thus enable the same to be controlled or regulated externally of the container which is a valuable feature inasmuch as it is impossible to regulate the movement of the strips within the container.

.11; is essential L0 the successful operation 0;

the breaker and the rolonged life thereof that the contact mem ers become separated without creating a heavy are, hence the breaker elements are necessarily of a light construction and cannot endure heavy arcing. In air and oil breakers, the circuit is broken at any point, an are formed, and is extinguished when the current reaches zero. On heavy overloads the arcs are very severe and would prove destructive in a vacuum circuit breaker of the character embodying my invention. Therefore, it becomes imperative that the contacts separate mechanically ata point just before reaching zero, the relay bemg incapable of accomplishing this result because of the limit of time involved, and due to variations in the current. I therefore, employ the current flowing through the breaker to accomplish the opening action thereof in a manner to prevent arcing during the separation of the contact members.

It is a well known fact that all current carrying conductors are surrounded by a circular magnetic field. This field is at zero when the current is at zero and likewise reaches its maximum force when the current is at its maximum power. Because of the overlapping relation between the contact strips 12 and the contact plates 13, a circular magnetic field is created by the passage of current therebetween and which is maintained at right angles with respect to the direction of flow of such current. The force of this field thus created by the contact members, when the same are in engaged position, binds the same together to form a ring of least magnetic reluctance, which of course varies depending upon the force of the current passing therebetween. Thus it is apparent that the circular magnetic field will operate to cause the contact strips 12 to remain in engaged position as long as the current passes through the breaker and particularly at a time when it is important to prevent the separation of the contact members to prevent in ury thereto, as for instance during the peak of a heavy current rush and the parts will thus be maintained in contact position in spite of the repulsion exerted by the external electro-magnet and will thus hold the breaker in closed position until the circular magnetic field and the current approaches zero. When the circular magnetic field becomes less than the repulsive field of the electromagnet, the contact strips 12 will separate at exactly the proper point, namely just before or at the zero current, thus eliminating any danger to the breakage due to the severe arcing. It is to be noted that the contact strips 12 must separate with an extreme rapid movement and this can only occur in a vacuum where there is no air resistance to impede the movement thereof.

In the operation of the device, with the contact strips of the breaker arranged in closed position, should a heavy overload of .current occur, the relay will be actuated so as to reverse the current in, and therefore the fields of coils A, thus causing repulsion between the strips 12 and the plates 13. However, due to the circular magnetic field caused by the current passing through the breaker, the strips will not become separated until the current passes its peak and declines towards zero, thus permitting the circular magnetic field to decline at the same time. As soon as the current approaches or reaches zero however, the influence of the circular magnetic field is reduced thereby permitting the dispelling force of the coil A to actuate the stripsand force the same out of contact.

It is obvious that the invention is susceptible to various'changes and modifications without departing from the spirit or scope of the invention as hereinafter claimed, and I accordingly claim all such forms of the device to which I am entitled.

I claim 1. In combination, a vacuum container, an electric circuit arranged to extend therethrough, a circuit breaker interposed in said circuit within the container and comprising a plurality of movable breaker strips and a plurality of contact plates engageable thereby, said strips and said plates constituting conductors for the current of the circuit and 'coacting when arranged in engaged position to create a magnetic field within the container around the strips and plates due to the current passing therethrough at right angles 4 with respect to the direction of flow of current through the circuit, a plurality of field coils disposed outwardly of the container, each having its opposite poles in magnetic relation to a strip and corresponding contact plate. means connecting'thc coils in a shunt circuit with said first named circuit, said coils being adapted to oppose or assist said magnetic, field within the container and means for connecting said coils with said circuit for actionby the variations in the load subjected thereon.

2. In combination, a frangible container having a vacuum created therein, an electric circuit extending through said container, a circuit breaking element interposed in said circuit within the container and comprising a plurality of movable breaker strips arranged inspaced parallel relation and a plurality of contacting plate members arranged in spaced parallel relation and staggered with respect to said strips and adapted to be engaged thereby and arranged so that each strip will engage a pair of the plates said strips and plates constituting conductors for the current 'of the circuit and adapted when in engaged position due to the current flow therethrough to create a magnetic field within the container around the strips at right angles with respect to the direction of flow of current in said circuit, av plurality of field 3. In combination, a frangible cylindricalcontainer having a vacuum created therein, a plurality of electric conductor wires extending within the container at each end thereof, a collecting ring connecting the wires at each end of the container, a pair of insulation rings mounted within the container in spaced relation, a plurality of breaker strips secured to one of said insulation rings and having the wires extending through one end of the container attached thereto, said strips being movable at one end and normally inclined in a direction away from the wall of the container, a plurality of contact plates secured in spaced relation to said other insulation ring in staggered position with respect to said strips and connected with the wires atthe opposite end of the container, said-strips constituting conductors for the current of the circuit whereby to produce a magnetic field around the strips for retarding opening movement thereof, a pair of metal bands arranged upon the outer wall of the container at a horizontal plane with respect to said strips, a plurality of cores connecting said bands, each of said cores having its opposite poles in magnetic relation with the corresponding strip and contact plates, a pair of field coils wound upon the yokes, a shunt circuit connecting sald coils with said first named circuit and means interposed in said shunt circuit adapted to reverse the polarity of certain of said coils and adapted through the reversing movement thereof to open or close said breaker strips.

4:. In a circuit breaker, a contact member, breaker strips cooperating therewith for opening and closing a main circuit, said strips constituting conductors interposed in the circuit whereby due to the current flowing therein produce a magnetiofield around the strips, a pair of field magnets arranged in a shunt circuit with: said main circuit and means for reversing the polarity of one of said magnets whereby to actuate said strips for moving the same into open or closed positlon. v

5. In a circuit breaker, a contact member, breaker strips cooperating therewith ,for opening and closing a main circuit, said strips constituting conductors interposed in the circuit whereby due to the current flowing therein produce a magnetic field around the strips for retarding the releasing movement of said strip and a plurality of field magnets arranged in a shunt circuit with said main circuit and normally arranged to coact with the magnetic field of said strips whereby to prevent the releasing of the same and means for reversing the polarity of one of said magnets whereby to oppose the magnetic field of said strips.

6. In combination, a vacuum container having main circuit wires passing therethrough, a circuit breaker interposed in the circuit within the container and comprising a plurality of contact members and a plurality of circuit breaker strips movable into open and closed position with respect thereto, said strips constituting conductors whereby due to a current flowing therein to produce a magnetic field about the strips, a plurality of field coils arranged in a shunt circuit with the main circuit and normally coacting with said magnetic field to retain the strips in closed position, said strips and contact members being in the path of the magnetic flux of the coils when energized and means for reversing the polarity of one of said coils whereby to move said strips into a closed position.

In testimony whereof I affix my signature.

CLARENCE KABELE. 

